The various aspects described herein related to an advanced manufacturing process and plant to recycle carpet.
Homes and businesses utilize carpet. These include residential broadloom carpet which has a taller pile and looser loop design and commercial broadloom carpet which has a short pile with a tight loop to withstand heavy foot traffic. Carpet is primarily made up of a face fiber (e.g. nylon or polyester), backing material (e.g. polypropylene), a filler (e.g. calcium carbonate) and an adhesive to bind the face fiber with the backing material (e.g. SBR latex). Post-consumer carpet (PCC) also has dirt from the carpet use.
When the carpet needs to be replaced, the carpet is discarded and fills the landfills or is sent to waste-to-energy facilities. There is also “pre-consumer carpet waste,” also known as “post-industrial carpet” (PIC) waste which has not been installed for consumer use. This includes carpet manufacturer trimmings, rejects, and overruns. Unless otherwise indicated, the use of the term PCC includes the ability to process PIC.
Efforts have been made to recover materials from PIC and residential PCC for recycling into other products but there are certain deficiencies in doing so. These efforts do not include the processing of commercial broadloom carpet which has unique recycling challenges. Additionally, these efforts primarily attempt to recover the face fiber (and sometimes the backing fiber) but not the calcium carbonate, SBR latex adhesive composite and dirt, collectively known as “ash” which is sent to landfills and thus losing over 40% of the amount of the PCC material that is actually recycled.
One common recycling method is shearing the face fiber pile from the surface of residential PCC. This approach only recovers the face fiber that extends above the carpet backing. It is labor intensive and not effective in recovering the significant portion of the face fiber found below the backing. The remaining material, commonly referred to as the carpet carcass is either disposed in landfills or sent to waste to energy facilities. There have been some attempts to also process the carcass material, however, these have similar deficiencies as that of processing whole carpet.
Other common methods attempt to recover the face fiber by processing the whole carpet. These methods include preparing a slurry of the size-reduced mixed fiber into a liquid medium and then separating it using a centrifuge. However, producing the size-reduced mixed fiber from the whole carpet and removing the nodules of calcium carbonate and SBR latex adhesive attached to the face fiber is done through numerous dry processing steps prior to slurrying the fiber and using screens to cut the fiber to shorter lengths This method has certain deficiencies including problems controlling the excessive particulate (i.e. dust) emissions that is generated from the numerous dry processing steps. These airborne particulates can impact worker health and ambient air quality.
Accordingly, there is a need in the art for an improved method of recycling carpet.